U.S. patent application number 10/278417 was filed with the patent office on 2004-04-29 for automatic additive replenishment system for ic engine lubricating oil.
Invention is credited to Schneider, Eric West.
Application Number | 20040079589 10/278417 |
Document ID | / |
Family ID | 32106543 |
Filed Date | 2004-04-29 |
United States Patent
Application |
20040079589 |
Kind Code |
A1 |
Schneider, Eric West |
April 29, 2004 |
Automatic additive replenishment system for IC engine lubricating
oil
Abstract
Method and apparatus for automatically replenishing additives
lost from the lubricating oil of an IC engine, by injecting
controlled quantities of the additive into the oil. The amount and
frequency of injection is controlled by either the operating
conditions of the oil (e.g. its thermal history), or changes the
properties of the oil (e.g. its electrochemical activity, or
dielectric constant).
Inventors: |
Schneider, Eric West;
(Shelby Township, MI) |
Correspondence
Address: |
KATHRYN A. MARRA
General Motors Corporation
Legal Staff, Mail Code 482-C23-B21
P.O. Box 300
Detroit
MI
48265-3000
US
|
Family ID: |
32106543 |
Appl. No.: |
10/278417 |
Filed: |
October 23, 2002 |
Current U.S.
Class: |
184/1.5 |
Current CPC
Class: |
F01M 9/02 20130101; F01M
11/0004 20130101 |
Class at
Publication: |
184/001.5 |
International
Class: |
F16C 003/14 |
Claims
1. Method for prolonging the useful life of lubricating oil in an
internal combustion engine, said oil when fresh comprising a first
concentration of at least one perishable, life-extending additive,
comprising storing a replenishable supply of liquid
additive-concentrate proximate said engine, said
additive-concentrate having a second concentration of said additive
greater then said first concentration, operating said engine under
a condition that depletes said additive from said oil, and
injecting said additive-concentrate into said oil at a rate
controlled by said condition so as to replenish additive lost from
said oil.
2. A method according to claim 1 wherein is provided by a hydraulic
head of said additive-concentrate provides pressure for said
injecting.
3. Method according to claim 2 wherein said additive is an
anti-oxidant and said condition is an oil temperature greater than
60.degree. C.
4. Method according to claim 2 wherein said supply of
additive-concentrate is stored within said engine.
5. Method according to claim 1 wherein a pump provides pressure for
said injecting.
6 Method for prolonging the useful life of lubricating oil in an
internal combustion engine, said oil when fresh comprising a first
concentration of at least one perishable, life-extending additive,
comprising the steps of: storing a replenishable supply of liquid
additive-concentrate proximate said engine, said
additive-concentrate having a second concentration of said additive
greater then said first concentration; empirically determining a
depletion rate of said additive from said oil under a certain
engine-operating condition, operating said engine under said
condition; monitoring said engine-operating condition while
operating said engine to determine when a predetermined amount of
said additive has been lost from said oil; and injecting a
predetermined quantity of said additive-concentrate into said oil
when said monitoring indicates that said predetermined amount has
been reached.
7. Method for prolonging the useful life of lubricating oil in an
internal combustion engine, said oil when fresh comprising a first
concentration of at least one perishable, anti-oxidant, comprising
the steps of: storing a replenishable supply of liquid
anti-oxidant-concentrate proximate said engine, said
anti-oxidant-concentrate having a second concentration of said
anti-oxidant greater then said first concentration; empirically
determining a depletion rate of said anti-oxidant from said oil at
various temperatures above 60.degree. C.; operating said engine at
said temperatures; monitoring the temperature of said oil while
operating said engine to determine when a predetermined amount of
anti-oxidant has been lost from said oil; and injecting a preset
quantity of said anti-oxidant into said oil when said monitoring
indicates that the additive needs replacing.
8. Method for prolonging the useful life of lubricating oil in an
internal combustion engine, said oil when fresh comprising a first
concentration of at least one perishable, life-extending additive,
comprising the steps of: storing a replenishable supply of liquid
additive-concentrate proximate said engine, said
additive-concentrate having a second concentration of said additive
greater then said first concentration; operating said engine under
conditions that deplete said additive from said oil; sensing a
physical property of said oil that is indicative of the depletion
of said additive in said oil, and injecting a predetermined
quantity of said additive-concentrate into said oil when said
sensing indicates that said depletion has reached a predetermined
amount.
9. Method according to claim 8 wherein said property is the
electrochemical activity of said oil.
10. Lubrication system for an internal combustion engine comprising
a sump for collecting oil drained from the engine's moving parts,
said oil, when fresh, comprising a first concentration of at least
one perishable, oil-life-extending additive depletable from said
oil under a certain engine-operating condition, a plurality of
passageways in said engine for delivering said oil to said moving
parts, a first pump for pumping said oil from said sump into said
passageways to lubricate said moving parts, a reservoir containing
an additive-concentrate having a second concentration of said
additive greater then said first concentration, a nozzle for
injecting said additive-concentrate into said oil, a conduit
communicating said reservoir and said nozzle for conducting said
additive-concentrate from said reservoir to said nozzle, and a
pressurizer for applying sufficient pressure on said
additive-concentrate to inject said additive-concentrate into said
oil to replenish additive lost from said oil.
11. A lubrication system according to claim 10 wherein said
pressurizer comprises a second pump, and said system further
comprises a sensor for monitoring said operating condition and
reporting said conditions to a controller, and a controller that
signals activation of said second pump to pump said
additive-concentrate into said oil when said conditions warrant the
addition of said additive to said oil.
12. A lubrication system according to claim 10 wherein, said
additive-concentrate comprises an anti-oxidant having a
predetermined viscosity that decreases as its temperature
increases, said pressurizer comprises a hydraulic head of said
additive-concentrate in said reservoir, and said nozzle comprises
at least one orifice immersed in said oil and sized to inject said
additive-concentrate into said oil at increasing rates as said
temperature increases from above 60.degree. C.
13. A lubrication system according to claim 11 wherein said sensor
is a temperature sensor for monitoring the temperature of said oil,
and said controller tracks the thermal history of said oil and
triggers said activation when said thermal history indicates that
cumulatively said oil has been used above 60.degree. C. for longer
than a predetermined period of time.
14. A lubrication system according to claim 10 wherein said nozzle
comprises a solenoid-operated valve, and said engine includes a
sensor for monitoring at least one engine operating condition that
causes depletion of said additive from said oil and reporting said
condition to a controller, and a controller that signals opening of
said valve to inject said additive-concentrate into said oil.
15. A lubrication system according to claim 14 wherein said sensor
is a temperature sensor, and said controller tracks the thermal
history of said oil and triggers said opening when said thermal
history indicates that said oil has been used above 60 .sup.co for
longer than a predetermined period of time.
16. A lubrication system according to claim 10 further comprising
an oil degradation sensor for monitoring the degradation of said
oil and triggering injection of said additive-concentrate into said
oil when said oil has degraded a predetermined amount.
17. An internal combustion engine comprising a crankcase for
collecting oil drained from the engine's moving parts, said oil
when fresh containing a first concentration of at least one
perishable, oil-life-extending additive depletable from said oil
under a certain engine-operating condition, a plurality of
passageways for delivering said oil to said moving parts, a pump
for pumping said oil from said crankcase into said passageways
under pressure to lubricate said moving parts, a reservoir within
said crankcase containing an additive-concentrate having a second
concentration of said additive greater then said first
concentration, a nozzle beneath said reservoir and immersed in said
oil in said crankcase for injecting said additive-concentrate into
said oil when the temperature of said oil exceeds 60.degree. C., a
conduit depending from said reservoir and communicating with said
nozzle for conducting said additive-concentrate from said reservoir
to said nozzle, a hydraulic head of said concentrate in said
reservoir for applying pressure on said additive-concentrate behind
said nozzle to inject said additive-concentrate into said oil to
replenish additive lost from said oil, a filler opening in said
reservoir for replenishing said additive-concentrate when depleted
from said reservoir, and a liquid level sensor communicating with
said reservoir for signaling the operator of the engine when the
level of additive-concentrate in said reservoir is low.
Description
TECHNICAL FIELD
[0001] This invention relates generally to lubrication systems for
internal combustion engines, and more particularly to method and
apparatus for automatically replenishing additives to the system's
lubricating oil that are lost during the operation of the
engine.
BACKGROUND OF THE INVENTION
[0002] Internal combustion (IC) engines (e.g. spark--, or
compression--, ignition engines) have a plurality of moving parts
that require lubrication to prevent damage to the engine.
Typically, such engines are provided with a lubrication system
comprising a sump (a.k.a. crankcase or oil pan) that collects oil
that drains from the moving parts, a plurality of passageways in
the engine's block and head for delivering oil to the moving parts,
and a pump for pumping oil from the sump through the passageways to
the moving parts. A filter is commonly located downstream of the
pump to remove unwanted particulates from the circulating oil.
[0003] The oil used to lubricate internal combustion engines
typically contains one or more perishable, life-extending
additives. By "perishable" additive is meant an oil additive that
either degrades, evaporates, is consumed or is otherwise lost
during operation of the engine, and needs replenishing if the oil
is to be effective. By "life-extending" additive is meant an
additive that forestalls the degradation of the oil, and maintains
its effectiveness for an extended period of time. Additives
commonly used with lubricating oils include varying amounts of such
things as anti-oxidants (e.g. ca. 0.5%-2.0% by. wt. aromatic
nitrogen compounds), ashless dispersants (e.g. ca. 2%-10% by wt.
polyisobutenyl succinimides), wear retardants (e.g. ca. 0.5-2.0% by
wt. zinc dithiophosphates), and detergents (e.g. ca. 2-10% by wt.
overbased sulfonates), inter alia. Zinc dithiophosphate (ZDP) also
functions as an anti-oxidant. The detergents and dispersants are
used to neutralize acids and suspend dirt particles that come
mainly from blow-by gases (i.e. gases that pass the rings during
combustion). The wear retardants, or anti-wear additives, form a
sacrificial, protective film on the metal surfaces to protect the
metal from wear. The anti-oxidants prevent oxidation of the oil at
normal (i.e. 60.degree. C.-130.degree. C.) oil temperatures, and
even more so at high (above 130.degree. C.) oil temperatures such
as can occur, for example, when operating the engine under severe
conditions (e.g. a car/truck pulling a heavy trailer up a steep
grade on a hot day). In this later regard, oil oxidizes more
rapidly at temperatures above 130.degree. C., than at normal
operating temperatures. With increased oil oxidation, comes an
undesirable increase in oil viscosity. The anti-oxidants retard
oxidation of the oil, but are consumed in the course thereof, and
hence are lost from the oil over time--especially at the higher
temperatures where the oil is most susceptible to oxidation. The
other additives while less sensitive to temperature, are
nonetheless lost from the oil over time, usually as a direct
function of engine speed and power.
[0004] Engine and vehicle manufacturers recommend that the oil be
changed at regular intervals to keep additive levels up. For
example, General Motors Corporation, assignee of the present
invention, recommends for some of its vehicles that: (1) under
normal driving conditions, the oil in its gasoline engines should
be changed every seventy five hundred (7,500) miles or 12 months
which ever comes first; and (2) under severe operating conditions
(e.g. frequent short trips in freezing weather, extended idling,
trailer towing, driving in dusty areas, frequent stop & go
driving, etc.) the oil should be changed every three months or
three thousand (3000) miles. Many vehicle operators forget to
change their engine oil regularly, which can be detrimental to the
engine. Accordingly, most automobile manufacturers have included
oil change warning/reminder systems in their vehicles. One such oil
change warning/reminder system is described in Schwartz et al. U.S.
Pat. No. 4,742,476, which is assigned to the Assignee of the
present invention, and is intended to be incorporated herein by
reference.
[0005] Schwartz et al., supra, recognized that excessive
degradation of the oil occurs at its temperature extremes. At low
oil temperatures (i.e. below about 60.degree. C.), fuel, water and
soot tend to accumulate in the oil, reducing its viscosity and
increasing wear. At high oil temperatures (i.e. above about
130.degree. C.), the anti-oxidants are depleted, the oil becomes
viscous and acidic due to oxidation and nitration, and insoluble
particles are deposited on the engine surfaces as varnish or
sludge. Acidic oil has a reduced ability to prevent rust and
corrosion. Schwartz et al., supra, predicts remaining oil life
based on the thermal history of the oil (i.e. time-at-temperature,
where time is determined in terms of either engine-revolutions or
mileage driven). More specifically, Schwartz et al. uses a
computer/controller that determines when an oil change is needed
based on empirical data and measured values of oil temperature and
engine speed (revolutions per minute) or miles driven. The number
of engine revolutions (or mileage driven) corresponding to the
maximum engine oil life that would occur if the vehicle were
continuously driven under conditions least degrading to the
lubricating ability of the oil is stored in a non-volatile memory
location in the controller. The oil's thermal history is
tracked--that is the temperature of the oil is measured, and the
duration the oil is at that temperature as recorded while the
engine is in operation. In each period of vehicle operation, the
stored number is decremented in accordance with an effective
engine-revolutions value determined in relation to the product of
measured engine revolutions (or mileage driven) and an
engine-oil-temperature-based penalty factor that is determined for
each engine and oil. When the oil temperature is in an
intermediate, ideal range, the penalty factor is set equal to
unity, and the effective engine revolution value accumulates at the
measured rate. When the oil temperature is outside the ideal range
(e.g. 60.degree. C.-130.degree. C.), the penalty factor is set to a
value greater than unity in accordance with a predetermined
schedule determined for each engine and oil so that the effective
engine revolutions value accumulates at a faster rate than the
measured rate. The penalty factor to be applied for each
temperature and oil is empirically determined for a particular
engine, and generally conforms to a stepped trace similar to that
designated as "A" of FIG. 5 hereof. The decremented stored number
represents the remaining life of the engine oil which is displayed
for the vehicle operator. A visual and/or audible warning
indication is given when the stored number is decremented below 10%
of its original value, indicating the need for an oil change.
Rather than directly measuring the oil temperature, the temperature
can be determined indirectly by calculations made from measurements
taken on other engine operating conditions (e.g. number of
combustion firings, coolant temperature, and engine rotational
speed), ala the method discussed in Schwartz et al U.S. Pat. No.
4,847,768, which is intended to be incorporated herein by
reference.
[0006] Sensors have been proposed for directly measuring the
condition (i.e. properties) of the oil. For example, Lee et al.
U.S. Pat. No. 5,200,027 discloses an oil degradation sensor that
uses two roughened, interdigitated electrodes to directly measure
the electrochemical properties of the oil. A saw-toothed voltage is
applied to the electrodes to generate an electrochemical current
that is measured. The magnitude of the measured current is
indicative of the condition of the oil--with lower currents
indicating newer/fresher oil and higher currents indicating
used/degraded oil. Lee et. Al U.S. Pat. No. 5,200,027 is intended
to be incorporated herein by reference. Moreover, Meitzer et al.
U.S. Pat. No. 4,733,556 (Mar. 29, 1988) teaches method and
apparatus for monitoring changes in the dielectric constant of
engine oil as an indicator of its remaining useful life. Meitzer et
al. U.S. Pat. No. 4,733,556 is intended to be incorporated herein
by reference.
[0007] It has been proposed to extend the time period between oil
changes by simply adding excess quantities of the additives to the
oil to insure that a sufficient amount of additive is present at
all times. Moreover, it has been proposed to periodically add the
additives to the oil regardless of the oil's usage history. Others
have proposed other techniques for adding makeup quantities of
additives to the oil. Rohde U.S. Pat. No. 4,066,559 fills an
additive-permeable, polyolefin container with the additive, and
immerses the container in the oil. At elevated temperatures, the
additive diffuses through the wall of the container into the oil.
The rate at which the additive diffuses out of the container is
reduced as the volume of the additive in the container is reduced,
and there is no way provided to replenish the additive in the
container when the additive content is depleted. DeJovine U.S. Pat.
No. 4,144,166, Lefebvre U.S. Pat. No. 5,591,330 and Lefebvre et al
U.S. Pat. No. 5,718,258 provide a soluble composite comprising oil
additives embedded in an oil-soluble polymer matrix. Oil passing
over the composite (e.g. in an oil filter or other canister)
dissolves the matrix polymer, and releases the additives into the
oil. The dissolved matrix material contaminates the oil, and
retards subsequent dissolution over time. All of these techniques
have the prospect of adding too much additive to the oil which has
a negative affect on vehicle fuel economy and tailpipe emissions.
Accordingly, it is desirable to have controlled addition of the
additives so as to keep the additive concentration in the oil
within prescribed limits.
SUMMARY OF THE INVENTION
[0008] The present invention prolongs the useful life of IC engine
lubricating oil, and extends the time period between needed oil
changes by adding makeup quantities of additives to the oil at
essentially the same rate as they are depleted from the oil so as
to keep the additive concentration in the oil in a prescribed range
over a prolonged period of time. More specifically, the present
invention contemplates method and apparatus for prolonging the
useful life of an IC engine's lubricating oil by replacing
perishable, life-extending additives as they are lost from the oil
during engine use. Process-wise the invention comprises: storing a
replenishable supply of liquid additive-concentrate (hereafter
concentrate) proximate the engine, which concentrate has a
concentration of additive greater then the concentration of the
additive in the oil; operating the engine under a certain operating
condition or conditions (e.g. temperature, power, speed etc.); and
injecting the liquid concentrate into the oil at a rate controlled
by that operating condition so as to replenish the lost additive at
substantially the rate it is lost from the oil. The injection
pressure may be provided by a pump, by a hydraulic head of the
concentrate in the additive supply system, or by engine-produced
pressures (e.g. exhaust gases).
[0009] According to one embodiment of the invention, the depletion
rate of a particular additive from the oil is determined
empirically under a certain engine-operating condition (e.g.
temperature, power. etc.) when the engine is running. To determine
when more additive is needed in an engine in service, this
engine-operating condition is monitored (i.e. by direct
measurement, or indirectly by calculation) to determine from the
empirical data when a predetermined amount of the additive has been
lost from the oil. When the monitored condition indicates that the
predetermined amount of additive has been lost, a dose (i.e. a
predetermined quantity) of the concentrate is injected into the oil
(i.e. "X" quantity of concentrate is added when "Y" amount of
additive has been lost).
[0010] According to another embodiment of the invention, the method
for prolonging the useful life of the lubricating oil comprises
sensing a physical property of the oil that is indicative of the
degradation of the additive in the oil (e.g. its electrochemical
activity, or dielectric constant), and injecting a dose of the
concentrate into the oil when the sensing indicates that the
degradation has reached a predetermined amount (e.g. X quantity of
concentrate is added when the oil has degraded 10%).
[0011] According to still another embodiment, the additive is an
antioxidant, and the concentrate thereof is injected into the oil
at a trickle rate determined by the viscosity of the concentrate,
the temperature of the oil, the size of the orifice(s) through
which the concentrate flows, and the hydraulic head of
concentrate.
[0012] The invention further comprehends apparatus for effecting
the aforesaid method. Apparatus-wise, the invention involves a
lubrication system for an internal combustion engine that
comprises: a sump for collecting oil drained from the engine's
moving parts; a plurality of passageways in the engine for
delivering oil to the moving parts; a pump for pumping the oil from
the sump into the passageways to lubricate the moving parts; a
reservoir containing a concentrate having a concentration of
additive therein that is greater then the concentration of the
additive in the oil; a nozzle for injecting the
additive-concentrate into the oil; a conduit communicating the
reservoir and the nozzle for conducting the concentrate from the
reservoir to the nozzle; and a pressurizer for applying sufficient
pressure on the concentrate to inject it into the oil to replenish
additive lost from the oil. In one embodiment, the presuurizer for
the concentrate is a second pump, and a sensor is provided to
monitor an engine operating condition (e.g. temperature) and report
it to a controller that signals activation of the second pump to
pump the additive-concentrate into the oil when the monitored
condition so warrants. According to another embodiment of the
invention, the nozzle comprises a solenoid-operated valve, a sensor
monitors an operating condition of the engine and reports it to a
controller which, in turn, signals opening of the valve to inject
the concentrate into the oil when the monitored condition so
warrants. Alternatively, the sensor may comprise a sensor that
monitors the condition of the oil (e.g. its electrochemical
activity or its changing dielectric constant) and triggers
injection of concentrate into the oil when the oil has degraded a
predetermined amount.
[0013] In still another embodiment: the concentrate comprises an
anti-oxidant, and is formulated to have a viscosity that decreases
as its temperature increases; the pressurizer is a hydraulic head
of liquid concentrate behind the nozzle; and the nozzle includes at
least one orifice immersed in the oil and sized to inject the
concentrate into the oil at increasing rates as the temperature of
the oil increases.
DESCRIPTION OF THE DRAWINGS
[0014] The invention will better be understood when considered in
the light of the following detailed description of certain specific
embodiments thereof which is given hereafter in conjunction with
the several drawings in which:
[0015] FIG. 1 schematically depicts one embodiment of the present
invention;
[0016] FIG. 2 schematically depicts another embodiment of the
present invention;
[0017] FIG. 3 schematically depicts still another embodiment of the
present invention;
[0018] FIG. 4 is an isometric view of an IC engine crankcase
according to a preferred embodiment of the present invention;
and
[0019] FIG. 5 are plots of oil temperature vs. (1) penalty factors,
and (2) additive makeup flow rate for one example of the present
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0020] FIGS. 1-3 depict an IC engine 2 having a V-block 4, a pair
of heads 6 and 8 and an oil pan/crankcase 10. The engine 2
internally includes a lubrication system 12 (here depicted external
to the engine) comprising an oil sump 14 in the crankcase 10, an
oil pump 16 for circulating the oil through the lubrication system,
an oil filter 18 for removing unwanted particulates from the oil,
and a plumbing system 20 communicating the sump 14, pump 16 and
filter 18 to a network of oil passages (not shown) within the
engine 2 for directing the oil to the various moving parts of the
engine that require lubrication.
[0021] FIG. 1 depicts one embodiment of the invention wherein the
crankcase 10 includes a sensor 22 for sensing a condition of the
oil (e.g. its temperature, electrochemical activity, dielectric
constant etc.) and reporting it to a controller 24 via signal 26.
Based on empirically generated data, and using lookup tables and
the like, the controller 24 determines when makeup additive is
needed When the controller 24 determines that makeup additive is
needed, it sends a signal 28 that energizes a pump 30 for a
duration of time sufficient to pump a predetermined quantity of
concentrate 32 from a reservoir 34 to injection nozzle 36 located
somewhere in the lubrication system (here shown, by way of example,
to be in the crankcase 10). The reservoir 34 is located proximate
the engine 2, and may be either inside or outside of the crankcase
10, as will be discussed in more detail hereinafter in conjunction
with FIG. 4. A liquid level sensor 46 in the reservoir 34 alerts
the engine operator when the concentrate 32 in the reservoir 34 is
low, and needs replenishing.
[0022] FIG. 2 shows another embodiment of the invention. The
embodiment shown if FIG. 2 is similar to that shown in FIG. 1
except instead of energizing the pump 30 to deliver a predetermined
quantity of additive-concentrate to the oil in the lubrication
system, the output of the pump 30 is plumbed to (1) circulate
concentrate 32 to and from the reservoir 34 under pressure, and (2)
divert some of the circulating concentrate to a solenoid-operated
injector valve 38 (akin to a fuel injector commonly found in IC
engine fuel systems) located somewhere in the lubrication system
(here shown at the crankcase 10). In this embodiment, the
controller 24 controls the pulse width (i.e. open time) or the
frequency of opening of the injector valve 38. Higher oil
temperatures will cause the valve to open more frequently.
Alternatively, the pump 30 may be eliminated, and the hydraulic
head of concentrate in the reservoir 34 used to provide the
pressure needed to inject the concentrate into the oil when the
injector valve 38 is opened.
[0023] The controller for the oil-change warning system of Schwartz
et al. U.S. Pat. No. 4,742,476 supra is conveniently adapted for
use with the present invention. In this regard, rather than sending
an audible or visual signal to the operator that an oil change is
needed, Schwartz et al's controller is programmed to automatically
dose the oil with concentrate. For example, in the case of an
anti-oxidant additive, dosing will preferably occur when the
anti-oxidant concentration in the oil falls below about 10% of its
prescribed concentration in the oil. Hence, a suitable controller
24 for the present invention will be essentially the same as that
employed by Schwartz et al. and includes conventional computer
control elements including a clock, a microcomputer, an
analog-to-digital converter (A/D), a counter (CTR), a non-volatile
memory, and an input/output device (I/O). The clock provides high
frequency pulses to the microcomputer, and all of the elements
communicate with each other via an address and control bus and a
bi-directional data bus. The analog output of the sensor (e.g.
temperature sensor) 22 is applied as an input to A/D where it is
converted to a digital format and made available for acquisition
via the data bus. The digital pulse train output of an engine speed
sensor (not shown) is applied as an input to the counter where it
is divided down to a rate of one pulse per engine revolution and
made available for acquisition via the data bus. An automatic reset
switch is provided that has a digital output that is inputted to
the I/O device and is triggered each time the oil is dosed to reset
the controller. The digital information for controlling the pump
30, or injector valve 38, is outputted as control signal 28 from
the I/O device. Eventually, the oil may have to be changed. When it
is, the oil change technician, or engine operator, actuates a
manual reset switch which is also inputted to the I/O device and
resets the controller.
[0024] The sensors are conventional sensors well known to those
skilled in the art. Thus for example, a temperature sensor may be a
varistor element housed in a conductive probe positioned in any
location (preferably the crankcase) where the measured oil
temperature is representative of the temperature of the oil in the
mainstream of oil flow. A speed sensor may be a variable reluctance
magnetic pickup cooperating with a toothed ferromagnetic wheel
coupled to the engine crankshaft. The manual reset switch may be a
conventional momentary-contact single-pole-single-throw switch
[0025] FIG. 3 shows still another embodiment of the invention. The
embodiment shown in FIG. 3 is particularly applicable where the
additive is an anti-oxidant (though not limited thereto). FIG. 3 is
similar to FIGS. 1 and 2 except that the controller 24, pump 30
(i.e. from FIGS. 1 and 2) and valve 38 are eliminated. Instead, the
injection rate of the concentrate 40 is controlled by a combination
of (1) the viscosity profile of the concentrate 40, (2) the engine
oil temperature, and (3) size of the orifice in the nozzle 44
through which the concentrate flows. The injection pressure is
provided by the hydraulic head of the concentrate 40 in the
reservoir 42. The anti-oxidant makeup rate is determined by the
concentration of the anti-oxidant in the concentrate and the flow
rate of the concentrate into the oil. Preferably, the anti-oxidant
makeup rate (e.g. see trace B of FIG. 5) will vary as a function of
oil temperature, and will approximate the rate at which the penalty
factor changes as a function of temperature (e.g. see trace A of
FIG. 5). The reservoir 42 contains a supply of the concentrate 40
at a level 50 above the level 47 of the oil in the sump 14. A tube
45 connects the reservoir 42 with the nozzle 44. The reservoir 42
communicates with the crankcase 10, above the oil level 47 and
concentrate level 50, by a vent tube 48 to maintain the same
pressure in the reservoir 42 and the crankcase 10. As a result, the
difference in height between the level 50 of the concentrate 40 in
the reservoir 42 and the level 48 of the oil in the crankcase 10
(i.e. the hydraulic head) provides the pressure needed to inject
the concentrate 40 into the oil. The concentrate flows through one
or more orifices (not shown) in the nozzle 44, which orifice(s)
is/are sized to deliver concentrate to the oil at a trickle only
when the temperature of the oil in the sump 14 is greater then a
predetermined threshold temperature (e.g. 70.degree. C.). The
concentrate is formulated such that its viscosity profile (i.e.
viscosity vs. temperature) will cause the concentrate to trickle at
increasing rates (and hence deliver more concentrate) through the
orifice(s) in the nozzle and into the oil as the temperature of the
oil increases above the threshold temperature. Below the threshold
temperature, no concentrate will flow. Above, but near the
threshold temperature (i.e. up to about 130.degree. C.),
concentrate will trickle into the oil very slowly. At higher oil
temperatures (i.e. up to 160.degree. C. or more) the concentrate
will trickle at a faster rate.
[0026] In all of the embodiments engine-generated pressure (e.g.
exhaust gases) may be substituted for the pump or hydraulic head of
concentrate. In this regard, exhaust gases may be routed to the
reservoir via a pressure regulator to provide the needed injection
pressure. Alternatively, the pressure regulator may be eliminated
and the reservoir provided with a pressure relief valve that holds
the reservoir at the pressure set by the relief valve.
[0027] Additive concentrations in the lubricating oil will vary
with the grade of the oil, and the composition of the specific
additive. In general, by weight: (1) anti-oxidants will constitute
about 0.5% to about 2.0% of the oil; (2) dispersants will
constitute about 2% to about 10% of the oil; (3) wear-retardants
will constitute about 0.5% to about 2% of the oil; and (4)
detergents will constitute about 2% to about 10% of the oil.
[0028] Preferably, the concentrate will comprise about 50% by wt.
to about 100% by wt.) of at least one anti-oxidant admixed with a
mixture of various lubricating oils that, together with the
anti-oxidant, provide the desired viscosity profile for a
particularly sized nozzle orifice. Concentrate formulations needed
to achieve a particular viscosity profile are determined
empirically. In this regard, various concentrations of anti-oxidant
are mixed with a diluent comprising various proportions of one or
more lubricating oils compatible with the engine lubricating oil.
The dilutent will preferably comprise different proportions of
different single SAE viscosity grade (e.g. SAE 5W-SAE 90W), and/or
multi SAE viscosity grades (e.g. 5W30) natural or synthetic
lubricating oils.
[0029] FIG. 4 depicts a preferred implementation of the embodiment
shown in FIG. 3 wherein reservoir 58 containing the concentrate is
located inside the oil pan 54 above the level of the oil 56
therein, and is preferably integral with the sidewall 60 of the oil
pan. The reservoir 58 will contain a supply of liquid, anti-oxidant
concentrate 62 comprising 75% by wt. Of a 50/50 admixture of a
phenolic or arylamine anti-oxidant and the balance a mixture of 80%
by volume SAE 0W20 viscosity grade oil, and 20% by volume SAE 5W30
viscosity grade oil formulated to have a viscosity profile adapted
to provide the temperature-dependant, anti-oxidant flow rate shown
in trace "B" of FIG. 5, when coupled with a nozzle having an
orifice 0.1 mm in diameter. A filler opening 64 provides access to
the inside of the reservoir 58 for replenishing the concentrate 62,
as needed. A liquid level sensor 66 is provided through the wall of
the reservoir 58 to alert the operator when the concentrate level
is low and needs replenishing. A vent tube 68 opens to both the
inside of the oil pan 54 and the reservoir 58 to equalize the
pressure therebetween. A concentrate supply tube 70 depends from
the reservoir 58, and terminates in a nozzle 72 located beneath the
surface 74 of the oil 56 in the oil pan 54. The reservoir 58 has a
relatively large horizontal cross-section compared to the inside
diameter of the tube 76, and the vertical length of the tube 70 is
long relative to the depth of the reservoir to minimize the change
in pressure of concentrate at the orifice in the nozzle 72, as the
concentrate is consumed, and hence maintain the hydraulic head of
the concentrate 62 substantially constant. The nozzle 72 comprises
one or more orifices (not shown) sized to cooperate with the
viscosity of the concentrate 62 to supply concentrate to the oil 56
at increasing rates as the oil temperature rises over the
temperature range 60.degree. C. to 160.degree. C.
[0030] While the invention has been described in terms of certain
specific embodiments thereof, it is not intended to be limited
thereto, but rather only to the extent set forth hereafter in the
claims which follow.
* * * * *